Flame retardants in US products are changing rapidly primarily because the most common flame retardants, polybrominated diphenyl ethers (PBDEs), were phased out from 2004 to 2013 because of reported evidence of liver and thyroid effects, developmental changes and neurotoxicity (EPA 2012). Many consumer products which previously used PBDEs now use alternative flame retardants. Occupational exposure to these alternative flame retardants is not currently well characterized. This project will assess exposure to nine alternative flame retardants plus a panel of PBDEs. Exposure will be assessed among workers involved in the manufacture, installation or use of goods containing these nine alternative flame retardants. These worksite categories will be included in the study: manufacture of products that use flexible polyurethane foams, plastics, or resins, fabrication and manufacture of rigid polystyrene foam, cutting, installing or spraying polyurethane foam insulation at construction sites, gymnasiums, manufacture of wire harnesses or printed circuit boards, and fire service. Site visits will optimize sampling methods to assess exposure to dominant flame retardants used in each worksite category. During FY 2015, the study went through external scientific peer review, tripartite review and was approved by the NIOSH Institutional Review Board. Several site visits were completed in FY15. Participant recruitment and field surveys are ongoing at additional sites.